Use __ANDROID__ instead of HAVE_ANDROID_OS.

Change-Id: I9967f3fd758c2a5b40be5b60ae72be7e2fb75136
diff --git a/libutils/Timers.cpp b/libutils/Timers.cpp
index fb70e15..201bc41 100644
--- a/libutils/Timers.cpp
+++ b/libutils/Timers.cpp
@@ -23,7 +23,7 @@
 #include <sys/time.h>
 #include <time.h>
 
-#if defined(HAVE_ANDROID_OS)
+#if defined(__ANDROID__)
 nsecs_t systemTime(int clock)
 {
     static const clockid_t clocks[] = {